Standard Extensions; Remote Internet Device Connections - 3Com NBX 100 Administrator's Manual

Standard Extensions

Remote Internet
Device Connections
Elsewhere on the LAN (local or remote), the destination telephone detects
its address, recovers the frames, extracts the bit stream, and reproduces
the voice.
While LANs have enough bandwidth to support uncompressed digitized
voice transfers, WAN bandwidth is less generous. For this reason,
compression is often used to squeeze the digitized voice into a smaller
bandwidth that can be carried across an Internet in smaller packets.
When an NBX call passes through an H.323 gateway, the ConneXtions
software performs an intermediate step that extracts the essential voice
information, encapsulates it in packets, and sends it across an IP network.
G.723 is a compression standard that represents each second of voice
conversation with 6.3 Kbps. ConneXtions software supports the use of
this compression standard. With more than one way to represent voice
(G.711 and G.723), H.323 gateways negotiate the type of compression
they use during each call setup. Negotiation ensures that the compression
on the transmit side matches the decompression processing on the
receiving side. With the frame and packet overhead, each G.723 channel
needs about 19.2 Kbps of the available bandwidth.
ConneXtions routes incoming H.323 calls to one designated extension,
usually the Auto Attendant. Callers can dial additional digits to redirect
calls to internal extensions, but cannot access outside lines by dialing 9.
A NBX system with a ConneXtions gateway can communicate with
remote H.323 devices other than NBX Business and Basic Telephones,
such as:
Wireless handsets
Personal computers
Ordinary telephones (POTS) with adapters
H.323 gatekeepers
Wireless Handsets
An emerging class of H.323 wireless handsets is being used by some
large outlet stores as portable PBX telephones. A ConneXtions H.323
server is well suited for use with these H.323 handsets.
Overview of H.323 415